1 /* mpfr_cmp_ui_2exp -- compare a floating-point number with an unsigned 2 machine integer multiplied by a power of 2 3 4 Copyright 1999, 2001, 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc. 5 Contributed by the AriC and Caramel projects, INRIA. 6 7 This file is part of the GNU MPFR Library. 8 9 The GNU MPFR Library is free software; you can redistribute it and/or modify 10 it under the terms of the GNU Lesser General Public License as published by 11 the Free Software Foundation; either version 3 of the License, or (at your 12 option) any later version. 13 14 The GNU MPFR Library is distributed in the hope that it will be useful, but 15 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 16 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 17 License for more details. 18 19 You should have received a copy of the GNU Lesser General Public License 20 along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see 21 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., 22 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ 23 24 #define MPFR_NEED_LONGLONG_H 25 #include "mpfr-impl.h" 26 27 /* returns a positive value if b > i*2^f, 28 a negative value if b < i*2^f, 29 zero if b = i*2^f. 30 b must not be NaN 31 */ 32 33 int 34 mpfr_cmp_ui_2exp (mpfr_srcptr b, unsigned long int i, mpfr_exp_t f) 35 { 36 if (MPFR_UNLIKELY( MPFR_IS_SINGULAR(b) )) 37 { 38 if (MPFR_IS_NAN (b)) 39 { 40 MPFR_SET_ERANGE (); 41 return 0; 42 } 43 else if (MPFR_IS_INF(b)) 44 return MPFR_INT_SIGN (b); 45 else /* since b cannot be NaN, b=0 here */ 46 return i != 0 ? -1 : 0; 47 } 48 49 if (MPFR_IS_NEG (b)) 50 return -1; 51 /* now b > 0 */ 52 else if (MPFR_UNLIKELY(i == 0)) 53 return 1; 54 else /* b > 0, i > 0 */ 55 { 56 mpfr_exp_t e; 57 int k; 58 mp_size_t bn; 59 mp_limb_t c, *bp; 60 61 /* i must be representable in a mp_limb_t */ 62 MPFR_ASSERTN(i == (mp_limb_t) i); 63 64 e = MPFR_GET_EXP (b); /* 2^(e-1) <= b < 2^e */ 65 if (e <= f) 66 return -1; 67 if (f < MPFR_EMAX_MAX - GMP_NUMB_BITS && 68 e > f + GMP_NUMB_BITS) 69 return 1; 70 71 /* now f < e <= f + GMP_NUMB_BITS */ 72 c = (mp_limb_t) i; 73 count_leading_zeros(k, c); 74 if ((int) (e - f) > GMP_NUMB_BITS - k) 75 return 1; 76 if ((int) (e - f) < GMP_NUMB_BITS - k) 77 return -1; 78 79 /* now b and i*2^f have the same exponent */ 80 c <<= k; 81 bn = (MPFR_PREC(b) - 1) / GMP_NUMB_BITS; 82 bp = MPFR_MANT(b); 83 if (bp[bn] > c) 84 return 1; 85 if (bp[bn] < c) 86 return -1; 87 88 /* most significant limbs agree, check remaining limbs from b */ 89 while (bn > 0) 90 if (bp[--bn] != 0) 91 return 1; 92 return 0; 93 } 94 } 95 96 #undef mpfr_cmp_ui 97 int 98 mpfr_cmp_ui (mpfr_srcptr b, unsigned long int i) 99 { 100 return mpfr_cmp_ui_2exp (b, i, 0); 101 } 102